Concealed trim clamp for electrical panelboards and other wiring cabinets

ABSTRACT

A concealed front cover or &#39;&#39;&#39;&#39;trim&#39;&#39;&#39;&#39; fastener for electrical panelboards or other wiring cabinets comprising four hooks fixedly attached to the inside of the front cover. Four support arms or brackets are attached to the inside of the panelboard or cabinet and have bent-over portions onto which the hooks of the front cover may be placed to support the front cover. The support arms are slidably adjustable in a direction perpendicular to the plane of the front cover (i.e., toward and away from the backwall of the cabinet). In one form, the cover is substantially larger than the cabinet, and when the cabinet is recessed into a wall, the outer edges of the front cover overlie peripheral portions of the wall and the cover is spaced away from the cabinet slightly. The support arms are drawn out to accommodate this spacing, and then fixed in place, such as by a nut and bolt. A locking screw mounted on a fixed portion of the cabinet is advanced after the front has been mounted in place and engages a bracket fixedly carried by the front cover and prevents the front cover from being raised so as to disengage the hooks from the adjustable support arms, thereby locking the front in place.

United States Patent [72] Inventor WernerA.I(rause West Hartford, Conn.[21 Appl. No. 867,778 22] Filed Oct. 20, 1969 [45] Patented Nov. 9,1971[73] Assignee General Electric Company [54] CONCEALED TRIM CLAMP FORELECTRICAL PANELBOARDS AND OTHER WIRING CABINETS 4 Claims, 5 DrawingFigs.

52 u.s.c1 220/3.s, 49/169, 174/50, 174/66, 220/24.3, 292/301,292/341.l8,317/l20 511 1111.01 1102;3/08 so FieldofSearch 220 3.s, 3.7,38,41, 55 1; 174/48, 50,66, 67; 317 1 17, 120;

[56] References Cited UNITED STATES PATENTS 288,189 11/1883 Sparks292/300 946,646 1/1910 Pratt..... 220/3.8 1,087,551 2/1914 Reed 292/3001,653,293 12/1927 Kendall 220/38 2,630,235 3/1953 Beber et a1... 220/3.83,465,914 9/1969 Pierson, .lr 220/24.3

Primary Examiner-Joseph R. Lecla1r Assistant Examiner-James R. GarrettAttorneys-Robert S. Smith, Robert T. Casey, D. M. Schiller,

Frank L. Neuhauser, Oscar B. Waddell and Joseph B. Forman 1 ABSTRACT: Aconcealed front cover or trim" fastener for electrical panelboards orother wiring cabinets comprising four hooks fixedly attached to theinside of the front cover. Four support arms or brackets are attached tothe inside of the panelboard or cabinet and have bent-over portions ontowhich the hooks of the front cover may be placed to support the frontcover. The support arms are slidably adjustable in a directionperpendicular to the plane of the front cover (i.e., toward and awayfrom the backwall of the cabinet). In one form, the cover issubstantially larger than the cabinet, and when the cabinet is recessedinto a wall, the outer edges of the front cover overlie peripheralportions of the wall and the cover is spaced away from the cabinetslightly. The support arms are drawn out to accommodate this spacing,and then fixed in place, such as by a nut and bolt. A locking screwmounted on a fixed portion of the cabinet is advanced after the fronthas been mounted in place and engages a bracket fixedly carried by thefront cover and prevents the front cover from being raised so as todisengage the hooks from the adjustable support arms, thereby lockingthe front in place.

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sum 2 UP 2 INVNTOR WERNER A. Kmquse A Tram/E Y BACKGROUND OF THEINVENTION 1 Field of the Invention My invention relates to electricalequipment enclosures, and more particularly to an improvement inelectrical circuit breaker panelboards of the type comprising a box forhousing the electrical components. Such boxes are often mounted in anopening in a supporting surface which is frequently a wall, and a frontcover panel or trim is detachably fastened to the open side of the box,with portions overlying the surrounding portions of the wall.

2. Description of the Prior Art In accordance with the prior art, avariety of different types of fastening means have been utilized for thepurpose of attaching a front panel to a box or enclosure. For example,with small electrical enclosures of the type commonly mounted on asurface of a wall, it is customary to attach the front cover to the boxby means of simple screw fasteners inserted through holes in the trimwhich engage tapped holes in flanges carried by the box. Although thisparticular means of fastening the front cover to the box will generallysuffice when used with small enclosures mounted on the surface of awall, it presents problems when used with larger box enclosures and alsowhen different mounting conditions are encountered. Thus, as the size ofthe enclosure increases, there is a corresponding increase in the sizeand weight of the front cover, and it is difficult to hold such coververtically in place during the process of installation while therequisite number of screw fasteners are installed. Another situationoften incurred, in which the use of simple screw fasteners has provenunsatisfactory, is where the box has been in a recess in a wall so thatits outer surfaceisbehind the plane of the outer surface of the wall. Inthis situation it is difficult to get the screw fasteners to engage thetapped hole in the flanges of the box enclosure. In addition, the use ofsuch screw fasteners ignores a potential safety hazard in that suchmeans are readily accessible from the exterior of the panelboard orelectrical control box. As a consequence, even though the door providedin the front for the purpose of gaining access to the interior of thepanelboard may be locked, there ,is nothing to prevent removal of thefront of the box by loosening the screw attaching means and therebygaining access to the electrical equipment housed therewithin. This isobjectionable wherever the panelboard is exposed to vandals or personswho would not take the requisite care required around electricalcircuitry.

One approach which has been taken by the prior art in an attempt toeliminate such problems involves an adjustable latch member such as thatdescribed in US. Pat. No. 3,] l6,08l issued Dec. 31, 1963 to L. C.Goodridge and ass gned to the assignee herein. The latch members whichengage the flanges of the box are operated by means of screws throughthe front cover. A disadvantage of using this particular type ofcover-attaching means is that to install the trim the latch members mustbe backed off sufficiently to clear the flanges of the box. As the latchmembers are tightened they may catch electrical wiring within theenclosure, inhibiting further operation and possibly damaging the wires.In addition, the operating means for the fastener is a screw headlocated on the outside of the panel where it is accessible and as in allsuch structures which utilized screw fasteners, it tends to detract fromthe appearance of the product.

For these reasons, front fasteners have been developed which are notaccessible when the door in the front is closed. Two forms of suchconcealed" front fasteners or clamps are illustrated and described inUS. Pat. No. 3,465,914, Pierson, and application US. Pat. No. Ser. No.739,250, Goodridge, filed June 24, l968, now Pat. No. 3,480,344 issuedNov. 25, 1969, both assigned to the assignee herein. Pierson discloses aconcealed trim clamp including a clamp member pivotally mounted on abracket on the inside of the front cover and having a nut pivotedthereon which receives the end of an elongated screw, the head of thescrew being accessible for operation only when the door is open.Goodridge shows a concealed fastener comprising a clamping arm pivotallysupported on a bracket carried by the inner surface of the front coveradjacent the door opening and an operating member pivotally supported onthe inner surface of the front cover for operating the clamping memberto and away from a clamping position against a flange of the panelboardenclosure.

OBJECTS OF THE INVENTION It is an object of the invention to provide anequipment enclosure of the type referred to which includes front panelclamps which are visible and accessible only when the door in the frontpanel is open. It is another object of the invention to provide animproved concealed front fastener for electrical panelboards for use inattaching a front to a panelboard whereby the front is attached to a boxso that the front cannot be removed when the door is closed.

A still further object of the present invention is to provide such aconcealed front fastener for electrical panelboards which simplifies thetask of attaching the front to the panelboard box while yet insuring asecure connection between the front and the box.

Another object of the present invention is to provide such a concealedfront fastener for electrical panelboards wherein the use thereofautomatically provides alignment between the front and the panelboardbox, and also provides adjustment for a substantial amount ofmisalignment between the box and the sidewall portions of the opening inthe wall on which the box is supported.

Still another object of the invention is to provide locking means inconjunction with a securing means that is strong enough to preventforcing open the front by anything less than drastic measures whichwould destroy the front itself.

Another object is to provide a structure having a minimum number ofsimple parts to maximize reliability and minimize manufacturing costs.

SUMMARY OF THE INVENTION In accordance with the present invention, thereis provided an electrical equipment enclosure including housing having aback wall and sidewall, and a separate detachably mounted front closuremember or trim having a door therein. A plurality of hook members arefixedly secured to the back side of the front cover. A correspondingnumber of adjustable support arms are attached to the inside of the boxwhere they may be positioned toward or away from the open front wall ofthe box. The hooks are provided with a tapered portion engaging theadjustable support arms and providing a positive connectiontherebetween. Blocking means is provided to force the front panel hookmembers against the adjustable support arms to further insure acontinuing positive connection therebetween.

The invention will be more fully understood from the following detaileddescription and its scope will be pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of anelectrical panelboard having concealed front fasteners in accordancewith the present invention;

FIG. 2 is a perspective view of the panelboard of FIG. I with the frontremoved;

FIG. 3 is a view in section along the line 33 of FIG. I with the coverin exploded relation;

FIG. 4 is a fragmentary perspective view on an enlarged scale of asingle concealed front fastener and an adjustable support bracketshowing alternate positions of the bracket; and

FIG. 5 is a view in section along the line 5-5 of FIG. I.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, theinvention is shown as incorporated in electrical circuit breakerpanelboard enclosure 10. The enclosure includes a housing 11 comprisinga back wall 12, a pair of sidewalls 13 and end walls 14, and a frontclosure means 15, comprising a front cover or trim panel 16 having anopenable door 17. The openable door 17 is retained by hinges 17a and alocking latch 17b.

Supported within the interior of the housing 11 is an inner cover plate18 which has a base portion 18A and upstanding flange portions 19. Thebase portion 18A is provided in a manner well known in the art withopenings or knockouts (not shown) adapted to receive raised portions ofthe circuit breakers 20 so as to render the circuit breaker operatinghandles 20a accessible for manual operation when the door 17 of the trimpanel 16 is open. The inner cover plate 18 may be supported within thehousing 11 in any suitable manner such as a plurality of brackets 21.

The trim panel 16 is detachably secured to the housing 11 by means of aplurality of hook members 22 and 23 which are mirror images of eachother. In the preferred embodiment two hook members 22 and two hookmembers 23 are provided with the former being adjacent one sidewall 13and the latter adjacent the opposed sidewall 13. The construction ofeach of the hook members 22 and 23 is substantially identical andreferring to FIGS. 3, 4, and 5, comprises a generally L-shaped piecehaving a tapered portion 22A extending generally perpendicular to theplane of the front cover or trim panel 16.

The hook members 22 and 23 each engage a corresponding adjustablesupport bracket 25 which comprises a member 26 of elongated sheet metalconstruction having end flanges portions 26a and 26b and an elongatedslot 260 which accommodates a bolt 27 which together with a nut 28 and asleeve 29 secure the member 26 to the sidewall 13. The mounting of eachof the adjustable support brackets 25 is substantially identical exceptthat the member 26 is reversed from the left side of the enclosure 10 tothe right side as viewed.

A locking means is provided to secure the hook members 22 and 23 againstthe adjustable support brackets 25. In the preferred embodiment, thelocking means comprises an L- shaped bracket 31 fixedly carried by theinner surface of panel front 16, and a machine screw 32 supported inthreaded engagement by nut 33 fixedly attached to upstanding flangeportion 19 of housing 11.

To assemble the trim panel 16 on the housing 1 l in the case wherein theenclosure 10 is surface mounted (mounted on a wall surface) rather thana flush mounted (recessed within a wall), the support brackets 25 do nothave to be adjustable, and they may instead be fixedly secured to thesidewalls 13 in a predetermined position to provide proper relationbetween the trim panel 16 and the housing 11. In that case, it is onlynecessary to engage the hooks 22 and 23 with the correspond ing bracketflange portions 26b and turn machine screw 32 to positively force orlock the hooks 22 and 23 against the bracket flange portions 26b Whereflush mounting of front panel 16 is desired or where the structureutilizes adjustable support brackets for the purpose of standardizingthe construction, it is necessary to loosen nut 28 on each adjustablesupport bracket 25 so that the member 26 may be slid to its positionfarthest out of the enclosure 10. A notch 13A is provided in flange 13Bof the sides 13 to slidably guide each member 26 so that the front panel16 may be hung by hooks 22 and 23 on the adjustable support bracketflange portions 26b without causing rotation of any one of the members26 about its mounting bolt 27. After attachment in this manner, the nuts28 of mounting bracket 25 are loosened slightly after gaining accessthrough the open door 17 and the front panel 16 is pressed into itsdesired ultimate position whereupon the nuts 28 are tightened to preventany further movement of members 26. Alternatively, where a standardinstallation is involved, the final position of the member 26 may beadjusted immediately. The ultimate osition may be flush with a wallwhich is supporting the enc osure 10 or may be abutting the front flangeportions of housing 11. The procedure for locking front panel 16 inplace is identical to that described above with respect to embodimentsutilizing a fixed support bracket 25.

To detach the trim panel 16 from the housing 11, the door 17 is firstopened, and then the locking screw 32 is turned out of engagement withlocking bracket 31 and then the front panel 16 is lifted off the supportbrackets 25.

While I have disclosed only one embodiment of my invention, it will beappreciated that many modifications thereof may readily be made by thoseskilled in that art, and I therefore intend by the appended claims tocover all such modifications as fall within the true spirit and scope ofmy invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. an electrical equipment enclosure comprising:

a. a housing having a rear wall, a plurality of sidewalls, and

an' open front;

b. front closure means for closing said open front of said housingcomprising a substantially flat member having a door therein, said flatmember having a rear surface and a front surface;

c. means mounting said door on said flat member for movement between anopen position and a closed position;

d. at least one pair of support brackets carried by said housing saidsupport brackets each having at least one generally planar surfacedisposed generally parallel to said front closure;

e. at least one pair of hook members fixedly carried on said frontclosure engaging said support brackets;

f. said support brackets being adjustable into and out of said enclosurein a direction normal to the plane of the open front of the housing.

2. An electrical equipment enclosure as set forth in claim 1 wherein atleast one additional pair of support brackets and one additional pair ofhook members are provided.

3. An electrical equipment enclosure as set forth in claim I whereinsaid enclosure also comprises locking means carried by said housing andmovable between a first position in which it obstructs movement of saidfront closure means in a plane parallel to said plane of said open frontof said housing to thereby prevent disengagement of said hooks from saidsuport brackets and removal of said front closure means, and a secondposition in which it permits movement of said front closure means in aplane parallel to said plane of said open front of said housing at leastenough to disengage said hook members from said support brackets.

4. An electrical equipment enclosure as set forth in claim 1 whereinsaid sidewalls of said housing include inwardly turned flanges having aplurality of notches, each of said notches slidably receiving a portionof one of said support brackets, and support means inside said housingslidably supporting each of said support brackets.

l I II! III

1. AN ELECTRICAL EQUIPMENT ENCLOSURE COMPRISING: A. A HOUSING HAVING AREAR WALL, A PLURALITY OF SIDEWALLS, AND AN OPEN FRONT; B. FRONT CLOSUREMEANS FOR CLOSING SAID OPEN FRONT OF SAID HOUSING COMPRISING ASUBSTANTIALLY FLAT MEMBER HAVING A DOOR THEREIN, SAID FLAT MEMBER HAVINGA REAR SURFACE AND A FRONT SURFACE; C. MEANS MOUNTING SAID DOOR ON SAIDFLAT MEMBER FOR MOVEMENT BETWEEN AN OPEN POSITION AND A CLOSED POSITION;D. AT LEAST ONE PAIR OF SUPPORT BRACKETS CARRIED BY SAID HOUSING SAIDSUPPORT BRACKETS EACH HAVING AT LEAST ONE GENERALLY PLANAR SURFACEDISPOSED GENERALLY PARALLEL TO SAID FRONT CLOSURE; E. AT LEAST ONE PAIROF HOOK MEMBERS FIXEDLY CARRIED ON SAID FRONT CLOSURE ENGAGING SAIDSUPPORT BRACKETS; F. SAID SUPPORT BRACKETS BEING ADJUSTABLE INTO AND OUTOF SAID ENCLOSURE IN A DIRECTION NORMAL TO THE PLANE OF THE OPEN FRONTOF THE HOUSING.
 2. An electrical equipment enclosure as set forth inclaim 1 wherein at least one additional paiR of support brackets and oneadditional pair of hook members are provided.
 3. An electrical equipmentenclosure as set forth in claim 1 wherein said enclosure also compriseslocking means carried by said housing and movable between a firstposition in which it obstructs movement of said front closure means in aplane parallel to said plane of said open front of said housing tothereby prevent disengagement of said hooks from said support bracketsand removal of said front closure means, and a second position in whichit permits movement of said front closure means in a plane parallel tosaid plane of said open front of said housing at least enough todisengage said hook members from said support brackets.
 4. An electricalequipment enclosure as set forth in claim 1 wherein said sidewalls ofsaid housing include inwardly turned flanges having a plurality ofnotches, each of said notches slidably receiving a portion of one ofsaid support brackets, and support means inside said housing slidablysupporting each of said support brackets.